Preparation of road beds in mountainous rocky terrain is extremely expensive. Timber and undergrowth must be cleared and removed. Rock and other unwanted overburden must be removed. The contour of the surface must be prepared. Stone, sand or other underlayment must be trucked to the site, smoothed, profiled and compacted. Finally, the road surface, whether asphaltic compositions, concrete or rock, must be laid.
All of these various functions are performed by specialized equipment, such as bulldozers, pan scrapers, cranes, excavators, drag buckets and graders. Highly paid personnel are required to operate this equipment. The cost of the equipment, the cost to transport the equipment to and from the work site, and operators wages all add to the expense of preparing the road bed.
The greatest number of miles of these mountainous roads are not paved for passenger car usage, but have a crushed rock surface and are used for access to timber harvesting sites, power line maintenance roads, fire prevention access roads and pipe line maintenance roads. The cost of the timber harvested and power and gas transmission costs are directly related to the cost of the roads necessary to secure, maintain or transport that resource.
One of the major expenses in preparing a road bed in rocky terrain is the removal of rock which is oversize for the bed surface and replacement of this rock material with properly sized rock. Currently, the least expensive method of road construction is to remove the oversize rock and deposit the rock in fill areas or in a waste tailing area. Properly sized crushed rock is then purchased from a supplier and trucked to the site as needed. An alternative is to temporarily erect a rock crushing machine in an area near the road work, carry the rock to this area, crush the rock and then transport the crushed rock back to the road bed. This approach reduces the transportation cost and eliminates the need to purchase crushed rock, but requires preparation of a site to erect the crushing apparatus which adds to the cost of preparing the road. Also, this alternative is often not practical because of the topography of the terrain and the unavailability of specialized rock crushing equipment.
It is, therefore, an object of this invention to provide an apparatus which can assist in preparing a road bed by crushing rock at the road building site.
It is a further object of the invention to have a self-propelled apparatus which loads and crushes rock without the need of additional equipment.
It is also an object of the invention to provide an apparatus which can perform excavating and road surface profiling.
A further object is to provide an apparatus wherein multiple road working functions ca be performed by a single operator from a single operating position.
Another object of the invention is to provide a road bed preparation device which can operate on unimproved surfaces.
Other objects and advantages of the present invention will be apparent from the following description of a preferred embodiment thereof and from the attached drawings.